502 Birds — Bed of Chalk-flints near Spa. 



tlie approximating point of which, according to M. Dumont's map, 

 is a little north of Limburg, twenty miles off, the next nearest, the 

 Losnee beds near Namur, and the next at Mons '(60-70 miles) , The 

 flints are generally of a yellow or brown colour, with a coating of 

 white chalk ; a few are purple and red and of different shades, and 

 they vary in size from that of a man's head to the smallest chip ; 

 they lie scattered over the cart roads crossing the moor, or cast 

 up upon the ditch banks, or imbedded here and there in their sides. 



They apjpear to contain a considerable variety of fossils, as in a 

 search of three or fom' hours I found from fifteen to twenty distinct 

 species of shells, echini, etc. They belong, probably, to an age 

 contemporary with the Upper or flinty Chalk of the British Isles. 



The most interesting inquiry, however, concerning them is as to 

 their origin in this spot. How did they come there ? Are they the 

 relics of the original chalk ocean left in situ where they were first 

 formed, and if so, were they once connected by a continuous band, 

 with the lai'ger masses of Maestricht or Losnee, the rest of which 

 has since been swept away ? or were they originally a small isolated 

 formation ? or did they form a shoal or shingle beach brought by 

 currents from elsewhere ? (The fact that, though most of the flints 

 are angular, some are rolled and waterworn might seem to favour 

 the latter hypothesis). Or, lastly, have they been brought to their 

 present position during the Glacial period by icebergs or floating ice. 

 In view of such a solution, one natually looks around for other signs 

 of glacial action, and they are apparently not wanting. 



Tho whole northern slope of the hills below the point where the 

 flints occur is covered for a mile or two, down to the bed of the 

 Wayai, with a thick coat of mud, including fragments of rock. It is 

 seamed in different directions by the hill streams, often to a depth 

 of 12 to 14 feet, and a cutting in the new railway to Luxemburg 

 near the river bed, displays a section of nearly 20 feet, without 

 reaching the bottom. A formation of such width and thickness can 

 hardly have been caused by the Wayai, which is an insignificant 

 stream only a few feet wide. It seems much more natural to sup- 

 pose that it is due to the melting of icebergs or float-ice. One can 

 imagine the frozen seas of the north sending out icebergs and fields 

 of ice over the area now lying between Maestricht and Spa, and if 

 the hills then had the same relative elevation as at present, a berg 

 would clear the summits south of the Yesdre, and then standing 

 upon the hills above Francorchamps and melting there, would leave 

 its deposit of chalk flints and pour down torrents of mud towards 

 the valley of the Wayai. 



Such may seem a not impossible origin of the deposit in question, 

 but should any experienced geologist, visiting Spa, think it worth 

 while to examine the locality, he might, perhaps, be able to decide 

 in a very short time whether this or any of the other hypotheses I 

 have suggested is the most natural. If the ice-origin of the flints is 

 correct, the limits of the sea during the Glacial period would have 

 to be extended one or two degrees southward of the line indicated 

 in Sir C. Ly ell's map (" Antiquity of Man," p. 276.) 



